Alberta Health Public Health Notifiable Disease Management Guidelines March 2017

Transcription

1 March 2017 Dengue Revision Dates Case Definition Reporting Requirements Epidemiology/Public Health Management Case Definition March 2017 March 2017 March 2017 Confirmed Case Laboratory confirmation of infection with or without clinical illness (A) : Detection of Dengue virus (DENV) nucleic acid (e.g., by RT-PCR) or isolation from an appropriate clinical specimen (e.g., blood, CSF, urine). Positive or equivocal DENV IgM antibody with a positive (B) Plaque Reduction Neutralization test (PRNT) and positive or equivocal Zika virus (ZIKV) IgM antibody with negative ZIKV PRNT. Probable Case (C) Laboratory evidence of infection with or without clinical illness (A) : Positive or equivocal DENV IgM antibody with a positive PRNT and positive or equivocal ZIKV IgM antibody with a positive ZIKV PRNT. A demonstrated seroconversion of DENV IgM confirmed by PRNT and positive or equivocal ZIKV IgM antibody with a positive ZIKV PRNT. *The following suspect case definition is provided as a guideline to assist with case finding and should NOT be reported to Alberta Health. Suspect Case Clinical illness (A) with ONE of the following: Travel to an area with DENV circulation within 2 weeks of symptom onset. Epidemiological link to a probable or confirmed case of dengue. equivocal or inconclusive DENV IgM antibody with pending PRNT. D [4] (A) Clinical illness: Fever or recent history of fever lasting 2 7 days with 2 or more of the following: headache, retro-ocular pain, muscle and joint pain, rash, hemorrhagic manifestations, leukopenia. (B) Positive PRNT is (i.e., 1:20). For the purposes of this case definition a negative PRNT is any value < 20 (i.e., <1:20 or negative). (C) Reported as both probable dengue and probable zika cases. (D) ZIKV IgM may be positive, equivocal, inconclusive or negative with pending PRNT. 1 of 7

2 Zika and Dengue Serological Lab Result Interpretation (1) Zika IgM Dengue IgM Zika PRNT* Dengue PRNT* Interpretation Confirmed case: zika (dengue not a <20 ** case) Confirmed case: dengue (zika not a <20 case) Probable cases: dengue /zika (specific virus cannot be identified due to crossreacting flavivirus antibodies),, <20 <20 Not a case: No evidence of zika or dengue Suspect case: zika or dengue, pending Negative Pending Pending Negative Positive Pending Pending Suspect case: zika or dengue, pending Suspect case: zika or dengue, pending Positive Pending Pending ** Pending <20 <20 Pending Testing not Negative Negative Testing not indicated indicated * Positive PRNT is. For the purposes of lab interpretation, a negative PRNT is any value less than 20. ** If clinically indicated, retesting is recommended for equivocal and inconclusive results. Suspect case: results (zika or dengue, pending) Not a case: Evidence of zika infection; likely remote infection > 3months (Not an acute case) Not a case: Evidence of dengue infection; likely remote infection > 3months (Not an acute case) Not a case: dengue/zika (specific virus cannot be identified due to cross-reacting flavivirus antibodies) Not a case: No evidence of zika or dengue Adapted from source: 1. Rabe IB, Staples JE, Villanueva J, Hummel KB, Johnson JA, Rose L, et al. Interim Guidance for Interpretation of Zika Virus Antibody Test Results. MMWR Morb Mortal Wkly Rep. 2016;65(21): Government of Alberta 2 of 7

3 Reporting Requirements 1. Physicians, Health Practitioners and others A physician, health practitioner or person in charge of an institution shall in accordance with Sections 22(1)(b) or 22 (1.1) and 22(2) of the Public Health Act (PHA), notify the Medical Officer of Health (MOH) (or designate) of the zone, of all confirmed and probable cases in the prescribed form by mail, fax or electronic transfer within 48 hours (two business days). 2. Laboratories All laboratories shall report all positive laboratory results by mail, fax or electronic transfer within 48 hours (two business days) to the MOH (or designate) of the zone and the Chief Medical Officer of Health (CMOH) (or designate). 3. Alberta Health Services and First Nations Inuit Health Branch (FNIHB) The MOH (or designate) of the zone where the case currently resides shall forward the initial Notifiable Disease Report (NDR) of all confirmed and probable cases to the CMOH (or designate) within two weeks of notification and the final NDR (amendment) within four weeks of notification. For out-of-province and out-of-country reports, the following information should be forwarded to the CMOH (or designate) by phone, fax or electronic transfer within 48 hours (two business days): name, date of birth, out-of-province health care number, out-of-province address and phone number, positive laboratory report and other relevant clinical/ epidemiological information Government of Alberta 3 of 7

4 Etiology DENV is a member of the Flaviviridae family. (1,2) There are four closely related but antigenically distinct virus serotypes: DEN-1, DEN-2, DEN-3, and DEN-4. Clinical Presentation The majority of individuals have no symptoms, especially children and those who have not had dengue previously. (3) Dengue fever is characterized by acute onset of frontal headache, retro-orbital pain, myalgias, arthralgias, minor hemorrhagic manifestations (e.g., petechiae, epistaxis, bleeding gums), rash, and low white blood cell and platelet counts. The acute symptoms last 3 7 days, although flu-like symptoms may persist for several weeks. Complications include dengue hemorrhagic fever (DHF), a severe and sometimes fatal form of the disease and dengue shock syndrome (DSS), which is DHF with circulatory failure. (3) DHF is defined by the following four World Health Organization Criteria: (4) 1. Fever or recent history of fever lasting 2 7 days. 2. Any hemorrhagic manifestation (at least one of the following): positive tourniquet test, petechiae, hematomas, epistaxis, gingival bleeding, and microscopic hematuria. More serious types of hemorrhage include vaginal bleeding, hematemesis, melena, and intracranial bleeding. 3. Thrombocytopenia (platelet count of 100,000/mm3). 4. Evidence of plasma leakage (at least one of the following): An elevated hematocrit % above the population mean hematocrit for age and sex. A decline in hematocrit after volume-replacement treatment of % of the baseline hematocrit. Presence of pleural effusion or ascites detected by radiography or other imaging method. Hypoproteinemia or hypoalbuminemia as determined by laboratory test. Mortality rates from DHF or DSS can be as high as 20% if untreated. (5) Pregnant women with DENV are at increased risk of miscarriage, premature birth and infants with low birth weight. (6) Reservoir DENV is primarily maintained in a human - Aedes mosquito cycle. (2,7) Populations of Aedes (aegypti or albopictus) mosquitoes are not established in Canada. The likelihood that Aedes mosquitos will become established in Canada is considered very low as they are limited by the lack of environmental and climate suitability here. (9) Transmission DENV is mainly transmitted by the bite of the infected Aedes mosquitos. (2) Although very rare, transmission may occur via needlestick, blood transfusion (especially in endemic countries), organ transplant and vertically, especially if the mother is acutely ill around the time of delivery. (1,2,7,8) The virus is sensitive to heat and is susceptible to many common disinfectants including ethanol, sodium hypochlorite, and glutaraldehyde. (1) It is, however, stable in dried blood and exudates for up to 9 weeks at room temperature. (1,9) Incubation Period The incubation period ranges from 3 14 days, but is typically 4 7 days. (2) Government of Alberta 4 of 7

5 Period of Communicability Dengue has a short period of communicability via blood, from shortly before until the end of the febrile period (usually 3 5 days). (2) Host Susceptibility Susceptibility is universal. Those living in or travelling to tropical areas are at highest risk of exposure to DENV. Those who have been previously infected, babies and young children are more likely to get severe infection. (2) Infection and recovery from one serotype was once thought to provide lifelong immunity to that serotype but no other serotypes. (10) Recent evidence suggests re-infection with the same serotype is possible however, more research is required. (11) Evidence also suggests that a subsequent infection by a different serotype increases the risk of acquiring DHF. (7) In addition, infants who were infected with DENV between 6 12 months of age and born to previously DENV-infected mothers are at increased risk for severe disease. (2) Incidence in Alberta Dengue has been notifiable in Alberta since (12) Between 2010 and 2015, less than 70 travelacquired cases were reported to Alberta Health. Dengue is not considered endemic in Alberta. Public Health Management Diagnosis PCR testing by ProvLab should be performed on serum collected during the first two weeks after symptom onset. (13) DENV IgM antibodies are usually detectable 6 7 days after the onset of illness and generally indicate a current or recent infection. Flavivirus antibodies can cross-react in the existing serological tests, especially those for IgM, resulting in some uncertainty in IgM results between ZIKV and DENV. Currently the two most frequently acquired flaviviruses in returning travelers are dengue and zika virus, and they do show cross-reactivity. Because of these cross-reacting antibodies with other flaviviruses, especially ZIKV at this time, cases with positive or equivocal serology are sent to the National Microbiology Laboratory (NML) in Winnipeg to be confirmed using PRNT. A serum specimen should be collected for acute phase DENV IgM antibody testing at least 5 days after of onset of clinical illness. A convalescent phase serum should be obtained at least 2 weeks after the first sample has been collected. However, PRNT is not always able to provide a definitive determination of the specific flavivirus causing a recent infection, especially if the person has a prior history of flavivirus infection (e.g., previous dengue or West Nile virus), is immunized against a flavivirus (e.g., yellow fever or Japanese encephalitis) or is currently co-infected with another flavivirus. These cases may have test results such as dengue IgM negative with positive PRNT results or positive PRNT results for both dengue and zika virus. (Refer to the ProvLab website for the latest information regarding diagnosis and testing) Government of Alberta 5 of 7

6 Key Investigation Confirm the diagnosis, if possible. Other arboviral diseases such as chikungunya, zika virus or West Nile virus and rash illnesses such as measles, rubella, parvovirus, enterovirus and malaria should be ruled out, if possible. (2) Determine where the case may have been exposed, taking into consideration the incubation period, reservoir, and mode of transmission, including: o History of recent travel to or emigration from an endemic area, o History of recent blood transfusion (within previous 21 days), o History of recent exposure to a confirmed case of dengue or traveller from an endemic area. o History of needle sharing. Case Management The following information should be provided to cases depending on their needs: o Dengue cases should avoid sharing needles. o Dengue cases should defer donating blood for 56 days after the onset of symptoms. (14) Treatment of a Case There is no effective, specific therapy for dengue. (2) Symptomatic care should be made available if the case develops dehydration or severe disease. (2) Acetylsalicylic acid (ASA) and other non-steroidal anti-inflammatory drugs (NSAIDs) are contraindicated due to anticoagulant effects that may aggravate the bleeding tendency associated with some dengue infections. (2,15) The risk of death can be reduced from 10% to 1% in severe cases if shock is recognized early and intensive supportive therapies are initiated quickly. (15) Management of Contacts There is no direct follow-up of contacts; however, it may be prudent to identify others who may have been exposed to the same source as the case to find undiagnosed cases. Preventive Measures Provide the following recommendations to persons travelling to endemic areas: o Consult a health care provider or visit a travel health clinic preferably six weeks before travel. o Protect yourself from mosquito bites: (16) remain in well-screened or completely enclosed, air-conditioned areas whenever possible, wear light-colored clothing and cover up as much as possible with long pants, longsleeved loose fitting shirts, shoes/boots (not sandals) and a hat. sleep under a bed net, preferably treated with insecticide, and use insect repellent (containing DEET or Icaridin), 15 minutes after sunscreen, on exposed skin and on clothing. There is currently no dengue vaccine licensed for use in Canada Government of Alberta 6 of 7

7 References 1. Public Health Agency of Canada (PHAC). Dengue fever virus (DEN 1, DEN 2, DEN 3, DEN 4) - Pathogen Safety Data Sheet [Internet] Available from: 2. Heymann DL, editor. Control of Communicable Diseases Manual. 20th ed. Washington, DC: American Public Health Association; Centers for Disease Control and Prevention (CDC). Dengue and Dengue Hemorrhagic Fever Information for Health Care Practitioners [Internet] Available from: 4. World Health Orgranization (WHO). Dengue haemorrhagic fever [cited 2016 Oct 24]; Available from: 5. WHO. Dengue and severe dengue [cited 2016 Oct 26]; Available from: 6. Paixão ES, Teixeira MG, Costa M da CN, Rodrigues LC. Dengue during pregnancy and adverse fetal outcomes: a systematic review and meta-analysis. Lancet Infect Dis. 2016;16(7): Thomas SJ., Endy TP., Rothman AL., Barrett AD. Flaviviruses (Dengue, Yellow Fever, Japanese Encephalitis, West Nile Encephalitis, St. Louis Encephalitis, Tick-Borne Encephalitis, Kyasanur Forest Disease, Alkhurma Hemorrhagic Fever, Zika). In: Bennett JE, Dolin R, Blaser MJ, editors. Mandell, Douglas and Bennet s principles and practice of infectious diseases. 8th ed. Philadelphia, P.A.: Elsevier Saunders; p Langgartner J, Audebert F, Schölmerich J, Glück T. Dengue virus infection transmitted by needle stick injury. J Infect [Internet] May [cited 2016 Sep 8];44(4): Available from: 9. Prado I, Rosario D, Bernardo L, Alvarez M, Rodríguez R, Vázquez S, et al. PCR detection of dengue virus using dried whole blood spotted on filter paper. J Virol Methods [Internet] Apr [cited 2016 Oct 13];125(1): Available from: Halstead SB. Etiologies of the experimental dengues of Siler and Simmons. Am J Trop Med Hyg [Internet] Sep [cited 2016 Sep 21];23(5): Available from: Forshey BM, Stoddard ST, Morrison AC. Dengue Viruses and Lifelong Immunity: Reevaluating the Conventional Wisdom. J Infect Dis [Internet]. Oxford University Press; 2016 Oct 1 [cited 2016 Sep 21];214(7): Available from: Alberta Health. Communicable Disease Reporting System (CDRS). Edmonton, AB; ProvLab. Update on testing for Zika, Dengue and Chikungunya Viruses [Internet] [cited 2016 Oct 25]. Available from: Canadian Blood Services. Personal Communication American Academy of Pediatrics. Dengue. In: Kimberlin DW, Brady MT, Jackson MA, Long SS, editors. Red Book: 2015 Report of the Committee on Infectious Diseases. 30th ed. Grove Village, I.L.: American Academy of Pediatrics; p Government of Canada. Insect bite prevention - Travel.gc.ca [Internet] [cited 2016 Oct 21]. Available from: travel.gc.ca/travelling/health-safety/insect-bite Government of Alberta 7 of 7